The goal is to study ethanol metabolism in the rat liver using in vivo NMR methods. These noninvasive studies will first require NMR developments in order to answer current questions about ethanol metabolism in both acute and chronic rats. The first specific aim is to develop NMR localization methods for following, non invasively, hepatic metabolism of 13C labeled precursors i.e. ethanol, alanine and acetate. This will be done by direct 13C NMR measurements and by heteronuclear edited 1H NMR spectra in which the high sensitivity of 1H NMR will be used to detect the 13C label flow into neighboring, coupled carbons. To quantitate these fluxes, it will be necessary to determine the fractional enrichment which will be done by NMR, and to specify the local volume giving rise to the signal. Simultaneously, the energy status of the liver will be monitored by 31P NMR. The second aim is to try to develop in vivo NMR methods for following the redox states. This will follow the indirectly responding ratios of lactate/pyruvate for cytosolic potential and of beta- hydroxybutyrate/acetoacetate for the mitochondrial. Direct 13C NMR and heteronuclear 1H-13C detection will be tried. The third aim is to follow the labeled precursors into TCA cycle pools of glutamate and, when possible, of glutamine and aspartate. Additional studies of the flows into pools of the ketone bodies and gluconeogenic products will be made. These experiments will utilize the methods developed in the first two specific aims to study both the acute response to ethanol and the response of rats administered two different chronic ethanol diets. The goal is to specify the differences in these pathways between the chronic and acute metabolism of ethanol. The fourth specific aim is to study the "empty calorie" effect in which chronic ethanol infusion reduces the energetic efficiency of ethanol metabolism. The pathways will be studied in conjunction with measurement, by 2H NMR, of the futile cycling between alcohol dehydrogenase and the MEOS enzyme that has been proposed to waste ethanol reducing equivalents in both rats and humans.